4-(2-aroylethyl)-1-piperazinecarboxylic acid esters



United States Patent O 3,284,453 4-(2-AROYLETHYL)-l-PIPERAZINECARBQXYLIC ACID ESTERS Andrew Stephen Tomcufcik, Old Tappan, N.J., Joyce Margaret Craig, Greenwich, Conn., and Stuart Dwight Willson, Park Ridge, N.J., assignors to American Cyanamid Company, Stamford, Conn., a corporation of Maine No Drawing. Filed Sept. 29, 1964, Ser. No. 400,248 19 Claims. (Cl. 260268) This invention relates to new compounds which are esters of 4-(2-substituted carbonyl ethyl)-1-piperazinecarboxylic acids. More specifically, the invention relates to esters of 4-(2-aroylethyl)-1-piperazinecarboxylic acid of the formula:

wherein R is lower alkyl phenyl, hydroxy phenyl, lower alkoxy phenyl, halophenyl, nitrophenyl, aminophenyl, acylaminophenyl or trifluoromethylphenyl, naphthyl, phenanthryl, biphenylyl, thienyl, pyridyl, or furyl, R is lower or phenyl(lower)alkyl.

The compounds of this invention are basic and form Water stable acid addition salts. The free bases are, in general, liquids or low melting solids, insoluble in water, and soluble in common organic solvents such as benzene, toluene, lower alkyl ethers, lower alkanols, acetone, ethyl acetate, and the like. Acid addition salts such as hydrochlorides, hydrobromides, sulfates, phosphates, acetates, tartrates, citrates, cinnamates, lactates, meconates, mucates, etc. are soluble in water and, more or less, in lower alkanols, but generally insoluble in petroleum ethers, ethers, benzene, toluene, xylenes, chloroform, methylene chloride, and the like.

The compounds of this invention may be prepared by reacting a l-substituted piperazine with an appropriate compound of the formula and formaldehyde, by the process described by Winstein, S., et al., J. Org. Chem. 11,218 (1946).

"ice

The above reaction can be illustrated as follows:

0 CHQCH:

II R C-CHzCHn-N wherein R and R are as hereinafter defined.

The reaction is conveniently carried out Within a temperature range of from about 75 C. to about 125 C. by stirring a refluxing solution of a salt of the l-substituted piperazine, the acetyl compound, and 37% aqueous formaldehyde in the approximate molecular ratios 1:l.1:1.14 in a solvent such as lower alkanol for minutes to eight hours, and thereafter cooling the reaction mixture -to about 0 to -10 C., causing the product, in salt form, to crystallize from solution. It is generally advantageous to add additional formaldehyde solution during the course of the refluxing reaction for higher yields. The products, as salts, are conveniently recrystal'lized from lower alkanols, most conveniently absolute ethanol.

The preparation of the compounds of this invention can also be carried out by the following reaction sequence:

wherein R and R are as defined above. The reactions are carried out most conveniently in lower alkanols at about C. to C. for periods of two to eight hours, in the presence of alkaline bicarbonates and carbonates, for example, as acid binders. Removal of the inorganic residue and the solvent leaves the desired compound as the free base which can then be converted to a stable acid addition salt by methods well known in the art.

The compounds of this invention have shown unusually high activities against a variety of yeasts, fungi, and parasites in standard in vitro measurements. The present compounds are therefore useful as antifungal agents, amebicides and trichomonicides. The following tabulation (Table 1) indicates the minimal inhibitory concentrations in micrograms per milliliter of compounds of the invention assayed against a variety of fungi:

TABLE I.MINIMAL INHIBITO RY CONCENTRATIONS IN MICRO GRAMS PER MILLILIIER OF MEDIUM H w 2 'T E 5 S 5 co m m '5: 9 H 5 I! d a g m p: A 92 g 8 5 E N a a E "a E: g as 8 ea e H g s a 1351 e o oo o 4 g .2 =1 g 5 'q a V 5 5 5 c Q 8 3 E i. E 2 1 01 5 ca E a a e 5 8 E a E .E w a e 3 Q g a a) E! ,g o a: g o .2 m a 5 0 :1 i; 2 .E 0% o :w .H be O O H c c a m on 2;: o g w 0 to gas "gel 020 gt a 83 go 3. a" a; at am 034 8? :12 SB; 6'5 :2 3H gm @N EN 3m 0 o o 2 e. 1 1 e 2 a. E 0 1 Ethyl 4-(2-p-chlorobenzoylethyl)-l-pipera- 16p 4p 4 K zinecarboxylate hydrochloride 31 8 l6 16 62 2 8 62 31 8 Ethyl 4-(2-p-anis0ylethyl)- -piperazine- 16p 62p 16p 0. 5p 1p 2p carboxylate hydrochlor' e 31 4 16 125 31 62 1 4 31 31 4 250 Ethyl 4-(2-p-ethoxybenzoyl)-1-piperazine- 16p 62p 0. 25p 0. 5p

carboxylate hydrochloride 31 31 31 125 31 62 1 2 62 62 4 Ethyl 4-[2-(4-biphenylylcarbonyl)ethyl]-1- 0. 5p 8p piperaziuecarboxylate hydrochloride 16 16 16 250 4 31 1 12 31 16 Ethyl 4-(2-m-chlorobenzoylethyl)-1-piperazinecarboxylate hydrochloride 62 31 62 31 8 8 62 Ethyl 4-[2-(p-bromobenzoyl)ethyl]-1-p1perazinecarboxylate hydrochloride 125 125 125 250 125 125 125 16 125 125 Ethyl 4-[2-(2,4,6-trimethylbenzoyl)ethyH-lpiperazineearboxylate hydrochloride 125 125 125 125 125 125 125 125 125 125 125 125 Ethyl 4-(Z-m-bromobeuzoylethyl)-1-piperazinecarboxylate hydrochloride 125 125 125 125 250 125 31 125 125 125 Chlorine Calcd.

Nitrogen Calcd.

6455001193 49996231163 4220991 13521 .955 .zsnnrlAsnrAmzfiznnnr 199759451 2562 2685345496839 A NJB JBAJ M NJ W W .JJ N MA N JD N W WB Hydrogen Oaled.

TABLE II Carbon Calcd.

Yield CHnCHz yl. ZchlorophenyL- l-naphth 3 2 4-chlor0pheny1 4-methox 2 5-dimothoxypheny1 Q-phenanthryl 4-fluor0phenyl.

3,4,5-trimothoxypheny1 4-hydroxypheny1 13. The compound ethyl 4-[2-(p-methylbenzoyl)ethyl]-1-piperazinecarboxylate hydrochloride. 14. The compound ethyl 4-(2-m-nitrobenzoylethyl)-1- piperazinecarboxylate hydrochloride.

15. The compound ethyl 4-(Z-p-nitrobenboylethyl)-1- piperazinecarboxylate hydrochloride.

16. The compound ethyl 4-(Z-o-chlorobenzoylethyl)-1- piperazinecarboxylate hydrochloride.

17. The compound ethyl 4-[2(p-propoxyhenzoyl)ethyl]-1-piperazinecarboxylate hydrochloride.

18. The compound ethyl 4-[2(2,4-dimethoxybenzoyl)- ethyl]-1-piperazinecarboxylate hydrochloride. 5O 19. The compound ethyl 4-[2-(3,4-dichlorobenzoy ethyl]-1-piperazinecarboxy1ate hydrochloride.

References Cited by the Examiner Jacobs et a1., Journ. Organic Chemistry, vol. 11 218-222, 1946.

ALEX MAZEL, Primary Examiner.

HENRY R. JILES, Examiner.

I. W. ADAMS, Assistant Examiner.

CHzC

wherein R is selected from the group consisting of lower alkyl phenyl, hydroxy phenyl, lower alkoxy phenyl, halo phenyl, nitrophenyl, aminophenyl, loweralkanoylaminophenyl or trifluoromethylphenyl, naphthyl, phenanthryl, biphenylyl, thienyl, pyridyl and furyl, R is selected from the group consisting of lower alkyl and phenyl(lower)- alkyl.

2. The compound ethyl 4-(2-p-chlorobenzylethyl)-1- piperazinecarboxylate hydrochloride.

3. The compound ethyl 4-(2-p-anisoylethyl)-1-piperazinecarboxylate hydrochloride.

4. The compound ethyl 4-(2-p-ethoxybenzoyl)-1-piperazinecarboxylate hydrochloride.

5. The compound ethyl 4-[2-(4-biphenylylcarbonyl)- ethyl]-1-piperazinecarboxylate hydrochloride.

6. The compound ethyl 4-(2-m-ch1orobenzoylethyl)-1- piperazinecarboxylate hydrochloride.

7. The compound ethyl 4-[l-(p-bromobenzoyDethyl]- l-piperazinecarboxylate hydrochloride.

8. The compound 4-[2-(2,4,6-trirnethylbenzoyl)ethyl]- l-piperazinecarboxylate hydrochloride.

9. The compound ethyl 4-(Z-m-bromobenzoylethyl)-1- piperazine carboxylate hydrochloride. 

1. A COMPOUND OF THE FORMULA: 1-(R1-CO-CH2-CH2-),4-(R2-OOC-)PIPERAZINE WHEREIN R, IS SELECTED FROM THE GROUP CONSISTING OF LOWER ALKYL PHENYL, HYDROXY PHENYL, LOWER ALKOXY PHENYL, HALOPHENYL, NITROPHENYL, AMINOPHENYL, LOWERALKYLANOYLAMINOPHENYL OR TRIFLUOROMETHYLPHENYL, NAPHTHYL, PHENANTHRYL, BIPHENYL, THIENYL, PYRRIDYL AND FURYL, R2 IS SELECTED FROM RTHE GROUP CONSISTING OF LOWER ALKYL AND PHENYL(LOWER)ALKYL. 